I bought and used a unibit and it worked just fine. To drill straight through the center I constructed a small jig from scrap wood. I had a small, maybe 10 x 12 inches, piece of partical board. I then took two approximately 3 by 8 pieces of the same material and cut a 45 degree chamfer off of the long edges. I glued those to the main piece to create v channel seperated just enough to support the PVC pipe. I clamped the jig to the drill press, centered the unitbit between the chamfers, drop the PVC pipe into the channel, and drilled away. The unibit cut nice and smoothly.

We had a radio club tape measure yagi build session. We built 10 yagis and all but one tuned near perfectly first time. The one that didn't tune was because we stripped back the insulation on the coax too far and our connections to the driven element were too long. We cut those down to minimum length required and all is good.

No matter what kind of drill you're using, the most important thing to do is never to force the bit into the work too fast. Light pressure, just enough to keep the bit cutting in, is best. It keeps the drill bit cool, doesn't dull it down so fast, and keeps the work from cracking or splintering.

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